The mentees REST endpoint (/w/rest.php/growthexperiments/v0/mentees) currently uses user language (whatever is in the user's preferences), and it does not respect uselang parameter passed to the Special:MentorDashboard (it does, however, respect uselang when it gets it directly, such as in this example).

Because it appears to be not practical to parse get parameters from JavaScript, let's just pass uselang parameter every time (populated with mw.config.get('wgUserLanguage')).

Acceptance criteria

• When an user goes to https://test.wikipedia.org/wiki/Special:MentorDashboard?uselang=fa, the registration column will use Farsi numerals (like at F35412996).